In recent years, problems of exhaustion of energy resources and global environmental issues such as increasing CO2 in the atmosphere have driven demands for development of clean energy. In particular, utilization of solar cells for photovoltaic power generation has been developed, been put into practical use, and been expanded as a new energy source.
In an exemplary conventional mainstream solar cell of such solar cells, a monocrystalline or polycrystalline silicon substrate has a surface (light-receiving surface) via which sunlight enters and in which an impurity of conductive type opposite to that of the silicon substrate is diffused to form a pn junction in the vicinity of the light receiving surface. In the silicon substrate, electrodes for one type are formed on the light receiving surface and electrodes for another type are formed on a surface (back surface) opposite thereto. In addition, in solar cells, generally, an aluminum paste is printed on the back surface of a p type silicon substrate and is sintered to form a high concentration p type impurity diffusion layer, thus allowing for generation of high power by means of a back-surface field effect.
Further, a plurality of the solar cells configured as above are electrically connected to one another via an inter-connector to form a solar cell string and the solar cell string thus formed is sealed by a resin to fabricate a solar cell module for photovoltaic power generation.
Patent Document 1: Japanese Patent Laying-Open No. 2-123769